The present invention relates to an automatic chemigation system and more particularly to a biological system incorporating features for the systematic application of chemicals in small, controlled amounts at frequent intervals.
A typical irrigation system for a lawn involves an underground sprinkler network which sequentially supplies water to zones in which the lawn is divided. Such an arrangement makes it possible to control accurately the delivery of water, avoiding watering which is too little and which would result in the grass having a weak surface root network subject to burnout and the production of thatch. Thatch prevents the growth of the grass plant and encourages weed emergence. It also is possible to avoid over watering which would effectively drown the grass plant or give rise to mold and fungus formation.
In order to supply nourishment to the lawn, fertilization is required. Fertilizing, as in watering, can be overdone or insufficient for optimum plant health. In the case of undernourishment the grass plant is starved and becomes weak and subject to replacement or encroachment by other heartier plants, especially weeds. When the grass plants are over fed, they are capable of absorbing only a finite amount of nitrogen which is stored in the root system. Over feeding promotes rapid plant growth until the stored nitrogen is depleted and the plant becomes weak because there is insufficient nutrients to maintain its overgrowth.
In order to prevent this "feast and famine" cycle and to avoid the labor of fertilizing lesser amounts more often, slow release fertilizers have been developed. These are typically applied to the lawn three to five times each year.
Depending on climatic conditions, such as excessive rainfall or unseasonable drought conditions, the "slow release" fertilizers deliver something other than optimum nutrients to the grass plants. As there is no way to anticipate with any degree of accuracy future weather conditions, fertilizers are often applied in excess quantitites to offset potential dry spells. This may not seem harmful, because excessive nitrogen is stored to the limit of the plants ability and any remainder passes through into the water table. However, this tactic causes inappropriate rapid growth, while also polluting the water table with chemical fertilizers and is wasteful of nutrients and costly.
For the reasons given above existing systems and methods for the fertilization of or delivery of chemicals to lawns and other botanical systems do not produce optimum results and have the drawbacks noted above.
Fertilization systems are shown in U.S. Pat. Nos. 4,026,673, 4,456,176, 4,545,396, and 4,558,715. None of the foregoing patents teaches or suggests the present invention.